You sure it's a female? I have some males that look like females but they are 100% male.. Put her with a larger female for a few days then condition them.. You may have to be rough with her.. Might sound mean taking her out of water for 40 seconds 1x a day for 5 days. But it works 80% of the time..

If the attaching is severe you may need to find another brood pair.. I have had that flaw many many times in my breeding with not only fish but exotic mammals also. Male attacking the female and chasing her around is common. So is fin nipping and fighting.

Females will flare at males. The thing is - how is she flaring? If she is constantly trying to break through head on, she is in fighting mode. But if she is swimming all over her tank and returns to flare, she is most probably in breeding mode (males must do this as well).

Give her time as you condition her further. Flare her to a mirror (since you don't have another female). place the mirror at the bottom part of the tank or cover the top part of the mirror. Give her only an inch of sight. Let her flare for 30 min or so. Then rest her in total isolation until the following day and try re-introducing them. See how they act/swim.

Now I change the male vt with a male pk nad she keeps swimming but not flaring,maybe at first.
How do you tell if the female is interested in him because i used the same male a few months ago and now i want to use the same pair again.

Both male and female must ... what I call.... flirt swim. That is; swim all over the tank in an "S" kind of way. This indicates that they are in breeding mode. If you flare uninterested couples for too long, they might stress (specially the female). When this happens, you have to isolate both for a few days to let them regain confidence/self esteem. After that exercise them regularly with another betta (of the same sex)/mirror.

While waiting for them to get into breeding mode, you can condition them with high protein food. When they start to flirt swim (even against the same sex) then you'll know they are ready to be introduced - put them in the breeding tank just before dark. She is a veteran breeder so she should spawn the following morning or so)

I just place the male in there for only 3 hours and he already built a large bubble nest.The female has vertical stripes already and they are swiming like an "s" already.Should i release the female now or should i wait.